类

类的工作方式类似于对象字面量类型和接口，但有一个例外：它们同时具有静态类型和实例类型。当比较一个类类型的两个对象时，只比较实例的成员。静态成员和构造函数不影响兼容性。

Classes work similarly to object literal types and interfaces with one exception: they have both a static and an instance type. When comparing two objects of a class type, only members of the instance are compared. Static members and constructors do not affect compatibility.

class Animal {
  feet: number;
  constructor(name: string, numFeet: number) {}
}

class Size {
  feet: number;
  constructor(numFeet: number) {}
}

let a: Animal;
let s: Size;

a = s; // OK
s = a; // OK